Video cassette recorders (VCR) are well-known consumer electronics items. These devices receive television signals from an antenna or cable television drop, and can record and play back programs at a user's convenience.
VCR's feature several different modes of operation. An operator can record an incoming program on a video cassette and simultaneously monitor the program on a television set. Alternately, a program already recorded on a video cassette can be viewed directly in place of incoming television signals. VCR's possess a switch (VCR/TV) which enables the operator to view either incoming TV signals or signals from the VCR. In the TV position, the viewer simply selects the channel using the television's own internal tuner in a conventional fashion. The VCR still receives signals from the TV antenna or cable drop, so a program can be recorded simultaneously on a video cassette from a channel selected with the VCR tuner.
Cable television companies offer "premium" channels wherein programs are transmitted in a scrambled mode, requiring a converter/descrambler for proper viewing. In operation, a viewer selects a channel for viewing which is descrambled as needed. These signals are subsequently presented either to the VCR or to the user's television directly, using a tuner internal to the converter/descrambler.
In their most basic configurations, VCR's and converters can be connected together in two straightforward ways; namely, with the converter output serving as the input source to the VCR, or with the VCR output serving as the input source to the converter. Both configurations suffer from well-known limitations.
When the output of the VCR is used to drive the converter, multiple unattended recording and tuning is possible with all non-scrambled ("clear") channels. In this configuration, a clear channel can also be recorded while viewing any other channel. In addition, if the VCR is equipped with a remote control, this unit will still be functional as will remote control through the cable television converter. However, recording of descrambled premium programs is not possible in this configuration, since descrambling occurs at the converter which is downstream from the VCR.
With the cable television converter wired upstream of the VCR, recording of descrambled premium channels is possible. However, since all channel selection must be made using the converter, the VCR remote control is rendered useless for channel selection. In addition, unattended recording on multiple channels is not possible since the cable television converter outputs its signal on only one channel (e.g., channel 3). As a result, desirable "cable ready" capabilities of a user's VCR and television set cannot be enjoyed. Such capabilities would normally allow the viewer to tune to all cable channels using his television or VCR tuning controls without the need to use the cable television converter for tuning clear channels.
In addition to the above, the United States Federal Communications Commission (FCC) has proposed a new regulation that would require cable television system operators to provide an "A/B switch" which would allow cable subscribers access to off-the-air television stations, particularly those no longer required to be carried on the cable system. Such a switch would be placed at the input of the user's television, allowing the user to switch between cable television signals or off-the-air signals from a conventional television antenna. Current cable television converters are not equipped to provide such an A/B switch.
It would be advantageous to provide a switchable signal source module for use with a cable television converter that would enable a user to switch between two different television signal sources, such as those provided by a cable system or a television antenna. It would also be advantageous to provide such a module that would enable a user to select between two alternate cable television sources.
It would further be advantageous to provide a module that improves compatibility between a cable television signal source and a variety of interconnected video appliances, such as a television set and VCR. In such a configuration, the cable ready features of the VCR or television set should be accessible to the user.
The present invention relates to signal source modules providing such advantages.